PINK BOLLWORM OF COTTON IN MEXICO. 11 
completed in an average of 13.3 days in the summer larvae. The sec- 
ond and third instars resemble the first in general appearance, and 
it is usually in the fourth or last larval stage that the larvae change 
to the characteristic pink color from which the name "pink boll- 
worm" is derived. Sometimes the pink color appears in the third 
instar, especially if development has been retarded in some way or 
the larva has been exposed to the air. The coloring first appears as 
transverse pink lines on the dorsal side of the segments and diffuses 
and deepens till there is only a small whitish or flesh-colored line left 
between the segments. The color seems to be more pronounced in 
the larvae which reach maturity in the late summer or early autumn 
and is a very deep pink or dull red. The head and thoracic shield 
are reddish brown with dark-brown mandibles and anal plate. The 
ventral side, legs, and prolegs are white to flesh colored, the legs and 
prolegs with brownish claws and crotches. The full-grown larva is 
cylindrical and measures about one-half inch in length. 
With the fourth stage the larva becomes very active again when 
disturbed and conceals itself as quickly as possible. A cocoon is 
spun attached to whatever object the larva is hiding in. The full- 
grown larva is never content outside a cocoon after it leaves a boll or 
seed. If it is taken from one cocoon it will immediately make another. 
How many times this will be repeated was not determined, but a 
perfectly healthy larva is rarely if ever found outside a cocoon, 
except when crawling from place to place. 
PUPA. 
The pupa is whitish, with faint markings of pink when first formed, 
turning to a mahogany brown as it dries and to a darker brown 
before emergence. It measures 8 to 10 mm. in length by 2.5 to 3 
mm. in width. The surface is covered with a fine velvety pubescence, 
the posterior end terminating in a short, stout, upwardly pointing, 
hooklike process. 
Pupation op Summer Larvae. 
When the summer larvae have completed their feeding, they cut 
to the outside of the boll directly through the carpel wall from the 
last seed attacked and drop to the ground for pupation. 
This exit hole through the carpel wall is usually round and clean 
cut and can be easily recognized as having been cut from the inside 
of the boll. Plate IT, A, gives a comparison of the entrance hole into 
the boll of the common bollworm, Chloridea obsoleta Fab., and the 
exit hole of the pink bollworm. The entrance holes of the common 
bollworm are larger, not so clean cut, and surrounded by a raised 
margin. They are not likely to be confused once both have been seen. 
In the case of the summer larvae, the holes made in the green 
cotton boll are always for the exit of the larvae, and not for the issuance 
